WO2020197609A2 - Compositions de revêtement auto-réparant - Google Patents

Compositions de revêtement auto-réparant Download PDF

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Publication number
WO2020197609A2
WO2020197609A2 PCT/US2020/012121 US2020012121W WO2020197609A2 WO 2020197609 A2 WO2020197609 A2 WO 2020197609A2 US 2020012121 W US2020012121 W US 2020012121W WO 2020197609 A2 WO2020197609 A2 WO 2020197609A2
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self
liquid medium
oil
coating composition
coating
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PCT/US2020/012121
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WO2020197609A3 (fr
Inventor
Jiaxing Huang
Chenlong CUI
Alane Tarianna O. LIM
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Northwestern University
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Priority to US17/419,522 priority Critical patent/US20220081777A1/en
Publication of WO2020197609A2 publication Critical patent/WO2020197609A2/fr
Publication of WO2020197609A3 publication Critical patent/WO2020197609A3/fr

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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C24/00—Coating starting from inorganic powder
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C26/00—Coating not provided for in groups C23C2/00 - C23C24/00
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/182—Graphene
    • C01B32/184—Preparation
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C30/00—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/30—Particle morphology extending in three dimensions

Definitions

  • Barrier coatings can retard corrosion by isolating underlying metal from reactive environments. Pinholes and other minor damages (e.g ., cracks and scratches) in the coating only expose small areas of metal. However, reactions at these sites can develop into dangerous localized corrosion, which can lead to catastrophic failure of the overall material system even with very little mass loss. Since these defects are hard to prevent, predict, or detect, responsive coatings that can self-repair are useful for mitigating localized corrosion.
  • low-viscosity fluid does not form stable coatings.
  • high-viscosity liquid e.g., a grease
  • continuous layers of low-viscosity oils can be stabilized on a surface with patterned pinning sites, which essentially restructures the liquid films into interconnected small reservoirs. These oil films can then act as protective barriers to isolate the substrate from water.
  • Such a composition comprises a liquid medium and a network of hollow capsules extending through the liquid medium in three dimensions, the network comprising a plurality of chains formed from the hollow capsules, aggregates of the hollow capsules, or both, wherein exterior surfaces of the hollow capsules of the plurality of chains define a plurality of channels filled with the liquid medium, and wherein the coating composition has a room temperature viscosity greater than that of the liquid medium.
  • Coated surfaces formed from the compositions and methods of protecting surfaces using the compositions are also provided.
  • FIGs. 1 A-1E demonstrate low-viscosity oil thickened by r-GO microcapsules.
  • FIG. 1 A shows a scanning electron microscopy (SEM) image and
  • FIG. IB shows a transmission electron microscopy (TEM) image of the r-GO capsules.
  • FIG. 1C shows the effect of particle (r-GO microcapsules) loading (top line) on the viscosity of a low-viscosity silicone oil (silicone oil only, bottom, dashed line).
  • FIG. ID shows an optical microscopy image taken near the edge of a thickened oil film on glass slide, confirming the existence of a network structure of the r-GO microcapsules. Thicker parts of the film are hard to image due to overlapping particles.
  • FIG. IE is a schematic of the network.
  • FIGs. 2A-2B demonstrate that an r-GO/oil barrier coating protects metal against corrosion.
  • FIG. 2A is a schematic drawing illustrating a 3-electrode electrochemical setup to evaluate the r-GO/oil film’s anti-corrosion performance in 1 M (3%) HC1.
  • FIG. 2B shows potentiodynamic polarization curves of an uncoated (left line) and coated (right line) A1 wires, showing that the r-GO/oil film indeed acts as a barrier and prevents the underlying A1 from reacting with HC1.
  • FIGs. 3A-3E demonstrate the self-healing property of an r-GO/oil coating.
  • FIG. 3A-3D are optical microscopy images showing that a scratch of about 0.5 mm wide fully heals in seconds. These images reveal that oil rapidly flows to the scratched area, followed by reorganization of particles to reestablish the network.
  • FIG. 3E shows the open-circuit current of an A1 wire coated with r-GO/oil immersed in 1 M (3%) HC1 during a scratch test. When the coating is scratched, a small area of the metal is exposed. The resulting local corrosion triggers a spike in the current that quickly dissipates within a few seconds, indicating that the coating has self-healed to restore its protective barrier property.
  • FIG. 4 demonstrates the exhaustive scratching and healing test performed.
  • a PDMS rod with a diameter of around 1 mm was attached to a clock hand to repeatedly scratch an r-GO/oil coated wire, at the same spot, once every minute. Every scratch removes a small piece of the coating, which repeatedly heals until there is an insufficient amount of r- GO/oil left to form a complete coverage on the wire.
  • the coating sustained 180 scratches. Unhealable damage on the coating becomes visible after 240 scratches.
  • FIGs. 5A-5C demonstrate that the r-GO/oil coating is scratch-tolerant and protects metal wires from localized corrosion.
  • FIG. 5A is a schematic illustration of the experimental procedure testing the effects of localized corrosion on the mechanical properties of brass wires. A wire is first coated with a barrier film, then scratched to expose a small area before being immersed in etching solution (5.5 M or 17% HC1). After etching, tensile tests are performed to directly evaluate corrosion-induced damage.
  • FIG. 5B shows representative stress-strain curves of an unetched wire, etched wire, etched wire with an unhealable coating, and etched wire with the r-GO/oil coating.
  • FIG. 5A is a schematic illustration of the experimental procedure testing the effects of localized corrosion on the mechanical properties of brass wires. A wire is first coated with a barrier film, then scratched to expose a small area before being immersed in etching solution (5.5 M or 17% HC1). After etching, tensile tests are
  • 5C is a bar graph summarizing changes in tensile strength and the mass of the wires tested in FIG. 5B.
  • the unprotected wire loses nearly 40% of mass and over 90% of strength after 1 week.
  • the polymer-coated wire has negligible mass loss, even after 2 weeks, but its strength is decreased by about half, due to localized corrosion at the scratch.
  • the wire coated with the self-healing r-GO/oil film retains its original mechanical properties and is not affected by the scratch.
  • FIG. 6 demonstrates that localized corrosion through pinholes can drastically degrade the properties of metal wires. Shown is the stress-strain curve of a brass wire protected with an unscratched polymer coating after being immersed in 5.5 M (17%) HC1 for 14 days, compared to that of a pristine wire. The etched wire experiences no detectable mass loss, but obvious reduction in strength and ductility.
  • the present approach is based on immobilizing low-viscosity liquids (e.g., oils) by a dynamic network of lightweight colloidal capsules such that a layer of modified liquid forms a stable coating on a variety of surfaces, including metal surfaces.
  • low-viscosity liquids e.g., oils
  • the liquid coating is thickened and becomes creep-resistant.
  • liquid trapped within the particle (capsule) network is still highly fluidic, and can readily flow and reconnect when the network is broken (e.g., by a scratch), and thus, is self-healing.
  • the coating compositions can be applied on demand on surfaces (even from underwater) to provide anti-corrosion barriers. As least some of the resulting coatings are pinhole-free, stable in high turbulent and highly corrosive environments, and can self-heal up to hundreds of times, facilitating their use in underwater anti-corrosion applications.
  • a self-healing coating composition comprises a liquid medium, e.g., an oil, and a network of hollow capsules extending through the liquid medium.
  • the phrase“liquid medium” refers to a material that is a liquid at the temperature at which the composition is being used to form the coating (or the temperature at which the coating is being used as an anti -corrosion barrier). This temperature may be room temperature (20 to 25°C).
  • the liquid medium has a particular viscosity (e.g., depending upon the type of oil selected) and the hollow capsules are composed of a solid material which assemble together to form a network extending in three- dimensions throughout the liquid medium.
  • This network effectively increases the viscosity of the liquid medium so that the self-healing coating composition forms a stable coating that resists flow when applied to a surface.
  • Pores/channels (defined in the network by exterior surfaces of walls of the hollow capsules) effectively encapsulate regions of the liquid.
  • the liquid within those pores/channels remains highly fluid.
  • the liquid medium of coating composition is viscous and gelled and resists flow.
  • Microscopically viscosity of the liquid medium is essentially unchanged.
  • the network itself is mobile and dynamic. Individual hollow capsules and aggregates thereof (and thus, the network) can be displaced by a mechanical force (e.g., scratching), resulting in corresponding changes to the physical structure of the network and to the pores/channels defined therein. During this process, some pores/channels may disappear, others may appear, and still others may change shape and/or dimension. At the same time, the liquid within those pores/channels may flow to fill regions previously occupied by hollow capsules. Each of these properties facilitates the“self-healing” nature of the present coating compositions.
  • the liquid medium of the coating compositions is characterized by a room temperature viscosity.
  • oils may be used for the liquid medium, including combinations of different oils.
  • the oil has a room temperature viscosity of at least 0.02 Pa-s, at least 2 Pa-s, or at least 20 Pa-s.
  • Illustrative oils include vegetable oils, sunscreen oils, mineral oils, silicone oils, and alkanes.
  • other liquid media e.g., liquid metals, may be used which may not be considered an oil but which have a similar range of room temperature viscosities.
  • the hollow capsules act as a thickening agent for the liquid medium.
  • the hollow capsules are discrete structures in the form of a shell, the walls of which enclose and define a hollow interior. However, the walls of the hollow capsules do not have to be completely enclosed; at least some of the hollow capsules may have walls which only partially enclose the interior. Exterior surfaces of the walls define the pores/channels described above, which become filled with the liquid medium.
  • the interiors of the hollow capsules are void spaces, when combined with the liquid medium to form the coating compositions, some of the liquid medium may penetrate walls of at least some of the hollow capsules, thereby filling or partially filling the interiors.
  • the hollow capsules generally do not contain or encapsulate other materials, by contrast to some existing coating compositions based on catalyst/healing agent-containing microcapsules.
  • the hollow morphology of the capsules (whether empty, filled, or partially filled) contributes to achieving the viscosity increases and self-healing properties for the coating compositions described herein.
  • the hollow capsules may be characterized by their overall shape and dimensions as well as the thickness of their walls.
  • the hollow capsules may be spherical in shape, but this does not mean perfectly spherical. In addition, the walls need not be perfectly smooth.
  • Hollow capsules may have an average diameter in the range of from 20 nm to 5 pm, from 20 nm to 3 pm, from 20 nm to 1 pm, from 20 nm to 500 nm, from 50 nm to 300 nm, or from 100 nm to 250 nm.
  • Hollow capsules may have an average wall thickness of no more than 25 nm, no more than 15 nm, no more than 10 nm, or in the range of from 1 nm to 15 nm.
  • the hollow capsules may assume other, non-spherical shapes. As described in the Example, below, since hollow capsules may be formed via a template material, the shape of the hollow capsules is generally determined by the shape of the template material itself. The average size of non-spherical shapes may be taken as the maximum distance across opposing sides and the average size may be within the ranges of the average diameter described above.
  • the hollow capsules may be characterized by a tap density as determined using the technique described in the Example, below.
  • the tap density may be in the range of from 0.05 g/cm 3 to 0.5 g/cm 3 . This includes a tap density in the range of from 0.1 g/cm 3 to 0.4 g/cm 3 , or from 0.2 g/cm 3 to 0.3 g/cm 3 . These relatively low tap densities contribute to achieving the viscosity increases and self-healing properties for the coating compositions described herein.
  • individual hollow capsules assemble together in the liquid medium, e.g., oil, to form chains of hollow capsules, aggregates of hollow capsules, chains of aggregates, and combinations thereof.
  • This provides an interconnected network of hollow capsules extending throughout the liquid medium in three dimensions.
  • the assembly of hollow capsules, and thus the network is random in nature, by contrast to some existing coating compositions based on lithographically defmed/printed vascular networks.
  • a pore defined by the network is labeled. These pores are highly irregular in shape and are not necessarily completely enclosed. As such, they may be characterized as a collection of tortuous, interconnected channels extending through the coating composition, the channels filled with the liquid medium of the coating composition.
  • FIG. 1C A schematic of the network of the coating compositions is shown in FIG. IE.
  • FIG. 1C demonstrates the surprising and remarkable ability of the network (in this embodiment, a network of hollow graphene capsules) to increase the viscosity of a liquid (in this embodiment, silicone oil). At the microscopic level, however, within a pore/channel of the network, the liquid remains highly fluid.
  • the loading of the hollow capsules in the liquid medium is selected to ensure formation of the network as well as to achieve the self-healing properties described above (insufficient loading inhibits network formation while overloading inhibits the mobility of the network and thus, reorganization of the network).
  • the loading may be selected to achieve a desired viscosity (or an increase in viscosity as compared to the viscosity of the liquid medium itself).
  • the hollow capsules are capable of greatly increasing the viscosity of the liquid medium even at very low loadings.
  • Loadings may be referred to as weight percentages, i.e., ((weight of hollow capsules/total weight of coating composition)* 100).
  • the loading is that which increases the viscosity of the liquid medium by a factor of at least 10, at least 100, at least 250, at least 500, at least 750, at least 1000, or at least 2000.
  • the increase in viscosity at a 5 wt% loading of hollow capsules is a factor of at least 10, at least 100, at least 250, at least 500, at least 750, at least 1000, or at least 2000. Viscosities may be determined as described in the Example, below.
  • the loading is that which provides the coating composition with a room temperature viscosity of at least 40 Pa-s, at least 60 Pa-s, at least 80 Pa-s, at least 100 Pa-s, or in the range of from 40 Pa-s to 100 Pa-s.
  • the hollow spheres may be composed of various materials, although the materials are generally wettable by the selected liquid medium, e.g., lipophilic for liquid media composed of oil/alkanes.
  • the term“wettable” may be quantified by contact angle
  • the hollow spheres are composed of graphene.
  • Methods for making graphene hollow spheres are described in the Example, below. In this Example, graphene hollow spheres are fabricated by spray-drying a mixture of 2 mg/mL graphene oxide with polystyrene stock solutions in a 10: 1 ratio, then reducing the collected graphene oxide capsules under argon at 600 °C for 4 hours to make hollow graphene spheres.
  • Other suitable materials include lipophilic polymers and silica (see
  • Example, below provided the materials are capable of achieving the hollow morphology, dimensions, and tap densities described above.
  • Cellulose and wood fibers may be used to make the hollow spheres.
  • the coating composition may further comprise one or more additives at various amounts, which may be useful for further tuning the properties of the coating composition.
  • the coating compositions may be used to form coatings on surfaces in order to protect those surfaces from external forces, e.g., mechanical forces and/or chemical forces (e.g., corrosion), which can undesirably alter the physical and mechanical properties of the unprotected surfaces.
  • coatings formed from the any of the disclosed coating compositions and coated surfaces are provided.
  • Various surfaces may be protected by the coating compositions, including metal surfaces.
  • Illustrative metals include Cu, Fe, Al, and alloys thereof, e.g., steel and brass.
  • the coating compositions may be applied using various techniques (e.g., brushing, spraying, dipping, etc.) so as to form a layer of the coating composition on the surface.
  • the thickness of the layer/coating generally depends upon the application technique and the viscosity of the coating composition. As described in the Example, below, application of the coating composition may be carried out even when the desired surface is submerged in a liquid, e.g., water.
  • the surface can be, but need not be, planar. Non-planar surfaces may also be coated and the resulting coatings may still exhibit any of the properties described below.
  • the coatings formed on surfaces using the coating compositions may be characterized by one or more of the following properties: stability, corrosion resistance, and self-healing. Tests for measuring these properties under certain conditions are described in the Example, below.
  • stability the coatings may exhibit high stability over extended periods of time in a variety of conditions.
  • an area of the coating composition deposited on a surface retains the same shape and dimensions after a period of at least 4 weeks, at least 5 weeks, or at least 6 weeks under exposure to air.
  • an area of the coating composition deposited on a surface retains the same shape and dimensions after a period of at least 30 min, at least 45 min, or at least 60 min under water.
  • an area of the coating composition deposited on a surface retains the same shape and dimensions after a period of at least 2 days, at least 3 days, or at least 5 days while being exposed to turbulent water having a linear velocity in the range of from 0.5 to 1 m/s. Coatings which exhibit these properties are described in the Example, below.
  • the coatings may exhibit an ability to resist corrosion over extended periods of time in a variety of conditions.
  • the coatings may exhibit an ability to resist corrosion over extended periods of time in a variety of conditions.
  • a wire coated with the coating composition exhibits a flat potentiodynamic polarization curve at 0 A (see FIG. 2B).
  • a wire coated with the coating composition remains intact after a period of at least 2 months, at least 3 months, at least 7 months, or at least 12 months while being immersed in a 20% HC1 solution. Coatings which exhibit these properties are described in the Example, below.
  • the coatings may exhibit an ability to self-heal, i.e., reform as described above, after exposure (including after repeated exposure) to an external force.
  • a scratch in a coated surface disappears in a short period of time (e.g., seconds, minutes) under air (FIGs. 3 A-3D) or water or acid. Reformation may also be evaluated via open-circuit measurements as shown in FIG. 3E.
  • a coated surface exhibits an ability to self-heal after being scratched at least 100 times, at least 150 times, or at least 200 times under water.
  • a wire coated with the coating composition exhibits no change in tensile strength after the coating is scratched and immersed in 5.5 M HC1 for 2 weeks (see FIG. 5B-5C). Coatings which exhibit these properties are described in the Example, below.
  • methods of protecting a surface comprises applying any of the disclosed coating compositions to a surface to form a coating thereon.
  • the method may further comprise applying an external force to the coating to create a defect therein, wherein the coating self-heals after a period of time.
  • the self- healing effectively eliminates the defect to restore the coating to its original form and having its original properties.
  • the external force is not particularly limited, nor is the type of defect.
  • the self-healing effectively eliminates the defect to restore the coating to its original form and having its original properties.
  • the self-healing may be confirmed using any of the techniques described herein (optical images, SEM images, open-circuit measurements, tensile strength measurements, etc.) to achieve any of the self-healing properties described herein.
  • Application of the external force and subsequent self-healing may be repeated multiple times.
  • Reduced graphene oxide (r-GO) capsules were made by an aerosol-assisted synthesis method based on a previous report, using a spray dryer (Buchi Nano Spray Dryer B-90). (K. Sohn et ah, Chem. Commun. 48, 5968-5970 (2012).) A mixture of 1 L 2 mg/mL GO sheets and 100 mL polystyrene colloids (200 nm diameter) was sprayed at 80 °C, which yielded GO-wrapped polystyrene beads. r-GO capsules were obtained by heating the product under argon at 600 °C for 4 hours, which reduced GO and removed the sacrificial polymer template.
  • the apparent density of the capsules was determined to be 0.12 g/cm 3 by measuring the volume of a known mass of powder within the end of a cylindrical pipette tip.
  • SEM images of the r-GO capsules were taken with a FEI Nova 600 SEM.
  • TEM images were taken with a JEOL ARM300F GrandARM transmission electron microscope. These particles were added to oil at various weight fractions to adjust viscosity.
  • oils such as household vegetable oils, household sunscreen oils, light mineral oils, and silicone oils were tested, all of which worked for self-healing coatings. Silicone oil was chosen as the model system due to its high stability against degradation and low solubility in water.
  • Low-molecular-weight (viscosity 20 cSt, i.e., around 0.02 Pa-s) and high-molecular-weight (viscosity 100,000 cSt, i.e., around 100 Pa-s) silicone oils were purchased from Sigma-Aldrich.
  • a number of metal wires were tested, including brass, copper, steel, and aluminum. The wires were briefly polished with sandpaper and washed with ethanol to remove any existing surface coating. Hollow spheres of poly(o- methoxy)aniline (average diameter: 2.27 pm, average wall thickness: 191 nm) and silica (average diameter: 3.94 pm, average wall thickness: 223 nm) were synthesized using methods in the literature. (P. J. Bruinsma, et al, Chem. Mater. 9, 2507-2512 (1997); and L. Zhang et al., J. Phys. Chem. C 113, 9128-9134 (2009).)
  • Viscosity measurement Viscosities of the r-GO/oil coatings were measured on an Anton Paar Physica MCR 300 rheometer with a cone-and-plate (lower loading levels) or parallel plate geometry (higher loading levels). Typically, 0.5 g of parti cl e/oil coating was subjected to shear rates from 0.1 to 100 rad/s to measure the resulting shear stresses. The viscosity at 0.1 rad/s was chosen for comparison.
  • Electrochemical tests The anti-corrosion performance of r-GO/oil on aluminum in a 1 M (3%) HC1 solution was evaluated using an Autolab electrochemical interface instrument (PGSTAT 302N).
  • the electrochemical cell (illustrated in FIG. 2A) was a three- electrode setup consisting of platinum (counter electrode), a freshly polished aluminum wire that was either bare or coated with r-GO/oil (working electrode), and Ag/AgCl (reference electrode).
  • the polarization curves (FIG. 2B) were measured from -0.3 VOCP to 0.3 VOCP at a scan rate of 0.001 V/s and a step size of 0.01 V.
  • FIGs. 3A-3E Visual and optical microscopy observation of self-healing property (FIGs. 3A-3E) r-GO/oil coating was applied onto a glass slide and swiped with a 200 pL pipette tip to generate scratches that were about 0.5 to 1 mm wide.
  • Optical microscopy images (Nikon Eclipse TE2000-U) were recorded using a monochrome interline CCD camera (Photometries, Cool SNAP HQ2).
  • Brass wires were first coated with r-GO/oil or Rust-Oleum 2X (a polymer-based anti-corrosion paint) and then scratched with a razor blade to generate small slits that were around 0.3 mm wide. Wires with scratched coatings were immersed into 5.5 M (17%) HC1 (1 week for uncoated wires, 2 weeks for coated wires). Stress-strain curves were obtained using a Bose ElectroForce 5500 tensile tester. SEM images of the wire surfaces after corrosion were taken with a FEI Nova 600 SEM. In control experiments, wires coated with the paint, but unscratched, were also immersed in HC1 to show the effect of pinholes, which are hard to prevent and detect during the coating process.
  • Rust-Oleum 2X a polymer-based anti-corrosion paint
  • Movie S2 Macroscopic visualization of self-healing r-GO/oil coating.
  • the movie showed that an r-GO/oil film on a glass microscope slide was scratched with a pipette tip and observed to heal within seconds. This healing process can be readily seen by eye.
  • the movie showed that a strip of PDMS attached to the“second” hand on a clock scratched a self-healing coating at one spot.
  • the clock can be left running to test the number of times the coating can be scratched at the same location.
  • Microcapsule-thickened oil Hollow microcapsules of reduced graphene oxide (r-GO) with an apparent density of around 0.12 g/cm 3 (FIGs. 1A and IB) were used in the studies below.
  • the microcapsules were made by spray-drying a mixture of graphene oxide sheets and polystyrene colloids of around 200 nm in diameter, followed by thermal annealing to reduce graphene oxide and remove the polystyrene beads (see Materials and Methods).
  • microcapsules were made of interconnected voids of around 200-250 nm in diameter with thin graphene walls of less than 10 nm. They were sufficiently robust and resilient during handling.
  • r-GO microcapsules can increase the viscosity of silicone oil by 1000 times at just about 5 wt. % loading.
  • Optical microscopy observation confirmed that the r-GO microcapsules indeed form an extended network in the oil (FIG. ID).
  • FIG. IE A schematic of the extended network is shown in FIG. IE. Heavier hollow microcapsules made of poly(o-methoxyaniline) or silica were also used in other experiments, but much higher loading levels ( e.g ., 15-35 wt.
  • r-GO microcapsules were required for the resulting coatings to achieve similar increases in viscosity.
  • the drastic thickening effect of r-GO microcapsules is primarily attributed to their light weight.
  • r-GO microcapsules also have a few other desirable properties.
  • prepared r-GO capsules absorb oil well, allowing them to stay wetted by and immersed in the oil rather than floating on the surface.
  • the black color of r-GO also facilitates direct visual inspection and optical microscopy observation of the oil coating.
  • a coated copper wire (1.02 mm in diameter) was immersed in a whirlpool generated by magnetic stirring, from 600 rpm to the maximum stirring speed of 1200 rpm. The coating remained intact after days of vigorous stirring. Under these stirring conditions, the linear velocities of water around the wire were estimated to be in the range of 0.5 to 1 m/s using a dye-tracking method (see Materials and Methods), which are on par with the typical flow rates of rivers.
  • FIG. 2A A 3 -electrode electrochemical cell (FIG. 2A) consisting of platinum as the counter electrode, an A1 wire as the working electrode, and Ag/AgCl as the reference electrode was used to evaluate the barrier performance of the r-GO/oil film in a solution of 1 M (3%) HC1.
  • the potentiodynamic polarization curve of a bare A1 wire (FIG. 2B, line on left) shows anodic and cathodic branches typically associated with the corrosion of a metal in a solution.
  • the r-GO/oil film adheres well to many types of metal surfaces (e.g ., Cu, Fe, A1 and their alloys), even those with complex geometries or sharp corners, on which oil film tends to dewet.
  • metal surfaces e.g ., Cu, Fe, A1 and their alloys
  • An example is demonstrated in tests in which an A1 foil boat was placed on a sea of 2M HC1. The boats were loaded with a methylene blue dye solution to indicate leakage. Without a barrier coating, the A1 boat was rapidly etched by HC1. It started to leak after 8 minutes and completely dissolved in 20 minutes. In contrast, the boat coated with an r- GO/oil film was well protected for over a day and remained intact after the dye solution or even the entire HC1 bath dried out.
  • the r-GO/oil coating can be conveniently applied to metal surfaces on demand, even from underwater, simply with a brush to yield a pinhole-free barrier coating (Movie SI) capable of stopping ongoing corrosion.
  • a bare A1 wire was also immersed, which immediately started to bubble due to reaction with HC1.
  • FIG. 3E (FIG. 3E) of an A1 wire coated with r-GO/oil immersed in 1 M (3%) HC1.
  • FIG. 4 illustrates an exhaustive scratch test on a r-GO/oil coated wire immersed under water.
  • a soft rod made of polydimethylsiloxane (PDMS) was attached to the minute hand of a clock, so that it could repeatedly scratch the immersed wire at the same location once every minute.
  • the r-GO/oil coating sustained scratching and self-healed repeatedly (see Movie S4). Therefore, although a small piece of the coating is removed during each scratch, the coating shown in FIG. 4 repeatedly heals even after 180 scratches. After 240 scratches, the damage on the coating becomes visible, when the remaining amount of r-GO/oil becomes insufficient to completely cover the wire.
  • FIG. 5B shows representative stress-strain curves of a number of brass wire samples before and after etching.
  • FIG. 5C compares the percentages of tensile strength and mass of these wires after etching, relative to those of the unetched wire. Without a protective barrier, the wire lost nearly 40% of its mass and over 90% of its strength after just 1 week.
  • the wire coated with a hard polymer barrier
  • silica particles VM-2270, Dow Coming, 5-15 microns particle size
  • 2-ethylhexyl trans-4- methoxycinnamate a commonly used sunscreen oil
  • the compositions included from about 3 to about 10 wt% of the silica particles.
  • the compositions were used to form coatings on an aluminum surface and similar results were obtained.
  • An advantage of the silica and polymeric capsules is their potential to be transparent or white in color. Such a coating may be colored by combining with the appropriately colored oil or an additional dye.

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Abstract

L'invention concerne des compositions de revêtement auto-réparant. Selon certains modes de réalisation, une telle composition comprend un milieu liquide et un réseau de capsules creuses s'étendant à travers le milieu liquide dans trois dimensions, le réseau comprenant une pluralité de chaînes formées par les capsules creuses, des agrégats des capsules creuses, ou les deux, les surfaces extérieures des capsules creuses de la pluralité de chaînes définissant une pluralité de canaux remplis du milieu liquide, et la composition de revêtement ayant une viscosité à température ambiante supérieure à celle du milieu liquide. L'invention concerne en outre des surfaces revêtues formées avec les compositions et des procédés de protection de surfaces mettant en œuvre les compositions.
PCT/US2020/012121 2019-01-04 2020-01-03 Compositions de revêtement auto-réparant WO2020197609A2 (fr)

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DE3150909C2 (de) * 1981-12-18 1983-12-29 Siemens AG, 1000 Berlin und 8000 München Füllsubstanz zum Längsdichten elektrischer und/oder optischer Kabel und Leitungen
DE3522751C2 (de) * 1985-06-26 1997-02-06 Henkel Kgaa Kabelfüllmassen
US20070293405A1 (en) * 2004-07-31 2007-12-20 Zhiqiang Zhang Use of nanomaterials as effective viscosity modifiers in lubricating fluids
WO2007082153A2 (fr) * 2006-01-05 2007-07-19 The Board Of Trustees Of The University Of Illinois Système de revêtement autorégénérant
US20070158609A1 (en) * 2006-01-12 2007-07-12 Haiping Hong Carbon nanoparticle-containing lubricant and grease
TWI364453B (en) * 2007-12-31 2012-05-21 Ind Tech Res Inst Lube oil compositions
DE112010000769T5 (de) * 2009-01-26 2012-07-26 Baker Hughes Incorporated Additive fur die Verbesserung von Motoröleigenschaften
US8222190B2 (en) * 2009-08-19 2012-07-17 Nanotek Instruments, Inc. Nano graphene-modified lubricant
KR101966272B1 (ko) * 2011-01-19 2019-04-08 프레지던트 앤드 펠로우즈 오브 하바드 칼리지 미끄러운 액체 주입된 다공성 표면 및 이의 생물학적 용도
US8691335B2 (en) * 2012-02-08 2014-04-08 Empire Technology Development, Llc Coating a substance with graphene
CA2847462A1 (fr) * 2013-10-28 2015-04-28 Institut National De La Recherche Scientifique Procede de production d'un revetement en graphene sur une surface en acier inoxydable
US9742001B2 (en) * 2014-08-07 2017-08-22 Nanotek Instruments, Inc. Graphene foam-protected anode active materials for lithium batteries
SG11201703909VA (en) * 2014-11-14 2017-06-29 Agency Science Tech & Res Hydrophobic coatings comprising reduced graphene oxide modified with a siloxane polymer
US10508204B2 (en) * 2015-12-02 2019-12-17 The Board Of Trustees Of The University Of Illinois Self-healing coating
US10214704B2 (en) * 2017-04-06 2019-02-26 Baker Hughes, A Ge Company, Llc Anti-degradation and self-healing lubricating oil

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